From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: Re: [PATCH v10 24/26] KVM: s390: device attrs to enable/disable AP interpretation Date: Tue, 25 Sep 2018 09:32:26 +0200 Message-ID: <62f0cacc-8338-9370-a4dc-12f793214c48@redhat.com> References: <1536781396-13601-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1536781396-13601-25-git-send-email-akrowiak@linux.vnet.ibm.com> <9263b698-1827-1b7f-28bf-75b44657dea2@redhat.com> <18a21cda-1da9-3bfb-7b34-80415b5457f9@linux.ibm.com> <172560fb-2c54-ea43-3401-f108cf2a0595@redhat.com> <1c0c5a2e-3ef4-e5f5-52b8-7aeddca1f472@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1c0c5a2e-3ef4-e5f5-52b8-7aeddca1f472@linux.ibm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Tony Krowiak , Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com, kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com, alex.williamson@redhat.com, pmorel@linux.vnet.ibm.com, alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com, jjherne@linux.vnet.ibm.com, thuth@redhat.com, pasic@linux.vnet.ibm.com, berrange@redhat.com, fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com, frankja@linux.ibm.com List-ID: On 24/09/2018 20:42, Tony Krowiak wrote: > On 09/24/2018 12:25 PM, Tony Krowiak wrote: >> On 09/24/2018 07:23 AM, David Hildenbrand wrote: > > (...) > >>> Will you also fixup this patch to expose KVM_S390_VM_CRYPTO_ENABLE_APIE >>> only if supported by HW? (ap_instructions_available) >> >> Given that this patch DOES expose KVM_S390_VM_CRYPTO_ENABLE_APIE only if >> supported by HW, I assume you are talking about >> KVM_S390_VM_CRYPTO_DISABLE_APIE. I didn't check >> ap_instructions_available() for disabling APIE because I didn't >> think it necessary given that ECA.28 will be set to 0 (intercept) by >> default, whether AP instructions are installed or not; so why not allow >> disabling apie. I suppose from the perspective of consistency, since the >> kvm_s390_vm_has_attr() function checks ap_instructions_available() for >> both attributes, then it probably makes sense to add that check to >> KVM_S390_VM_CRYPTO_DISABLE_APIE here. Then again, we could make a change >> in ap_instructions_available() to allow KVM_S390_VM_CRYPTO_DISABLE_APIE >> regardless of whether AP instructions are available. It boils down to >> whether APIE needs to be dynamically disabled at some point when it has >> been enabled. The only case I can think of where that may be necessary >> is if a guest is migrated to a system without AP instructions. I don't >> think that can happen and may even be protected against precisely >> because the VM attributes won't be available on the target system due to >> no AP instructions. What say you? >> > David, > > I'm sorry, I misinterpreted what you were asking for. Check out the > fixup! patch below and let me know if that is what you are looking for. > If so, I will integrate that change and post v11 tomorrow (Tuesday 9/24). > > -----------------------------------8<----------------------------------- > > From: Tony Krowiak > Date: Mon, 24 Sep 2018 14:18:37 -0400 > Subject: [FIXUP v10] fixup! KVM: s390: device attrs to enable/disable AP > interpretation > > --- > arch/s390/kvm/kvm-s390.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index 6654bb1fc26a..a528558baa78 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -901,6 +901,10 @@ static int kvm_s390_vm_set_crypto(struct kvm *kvm, > struct kvm_device_attr *attr) > kvm->arch.crypto.apie = 1; > break; > case KVM_S390_VM_CRYPTO_DISABLE_APIE: > + if (!ap_instructions_available()) { > + mutex_unlock(&kvm->lock); > + return -EOPNOTSUPP; > + } > kvm->arch.crypto.apie = 0; > break; > default: > @@ -1509,9 +1513,11 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, > struct kvm_device_attr *attr) > case KVM_S390_VM_CRYPTO_ENABLE_DEA_KW: > case KVM_S390_VM_CRYPTO_DISABLE_AES_KW: > case KVM_S390_VM_CRYPTO_DISABLE_DEA_KW: > + ret = 0; > + break; > case KVM_S390_VM_CRYPTO_ENABLE_APIE: > case KVM_S390_VM_CRYPTO_DISABLE_APIE: > - ret = 0; > + ret = ap_instructions_available(); Just a little remark, I guess we want to report 0 if available and -ENXIO if not. -- Thanks, David / dhildenb